Sporadic CJDThe possibility that at least some cases of apparently sporadic CJD might be due to infection by sporadic cases of BSE cannot be dismissed outright. Screening programs needed to identify sporadic BSE have yet to be implemented, and we know from already extant testing programs that at least a proportion of infected animals have no symptoms and thus would never be identified in the absence of systematic testing. Thus, sporadic BSE (or for that matter, sporadic disease in any mammalian species) might be occurring on a regular basis at perhaps the same annual frequency as sporadic CJD in humans, that is, in the range of 1 case per million animals.

Whether humans might be more susceptible to atypical forms of BSE cannot be answered at this time. Experimentally transmitted BASE shows shorter incubation periods than BSE in at least 1 breed of cattle, bovinized transgenic mice, and Cynomolgus monkeys (12,13). In humanized transgenic mice, BASE transmitted, whereas typical BSE did not transmit (13). Paradoxically, the other major phenotype (H) showed an unusually long incubation period in bovinized transgenic mice (12).

The limited experimental evidence bearing on a possible relationship between BSE and sporadic CJD is difficult to interpret. The original atypical BASE strain of BSE had a molecular protein signature very similar to that of 1 subtype (type 2 M/V) of sporadic CJD in humans (5). In another study, a strain of typical BSE injected into humanized mice encoding valine at codon 129 showed a glycopattern indistinguishable from the same subtype of sporadic CJD (15). In a third study, the glycopatterns of both the H and L strains of atypical BSE evidently did not resemble any of the known sporadic CJD subtypes (12).

To these molecular biology observations can be added the epidemiologic data accumulated during the past 30 years. The hypothesis that at least some cases of apparently sporadic CJD are due to unrecognized BSE infections cannot be formally refuted, but if correct, we might expect by now to have some epidemiologic evidence linking BSE to at least 1 cluster of apparently sporadic cases of CJD. Although only a few clusters have been found (and still fewer published), every proposed cluster that has been investigated has failed to show any common exposure to bovines. For that matter, no common exposure has been shown to any environmental vehicles of infection, including the consumption of foodstuffs from bovine, ovine, and porcine sources, the 3 livestock species known to be susceptible to transmissible spongiform encephalopathies. Additional negative evidence comes from several large case-control studies in which no statistically significant dietary differences were observed between patients with sporadic CJD and controls (16,17).

On the other hand, the difficulty of establishing a link between BSE and CJD may be compounded by our ignorance of the infectious parameters of a sporadic form of BSE (e.g., host range, tissue distribution of infectivity, route of transmission, minimum infectious dose for humans, whether single or multiple). Presumably, these parameters would resemble those of variant CJD; that is, high infectivity central nervous system and lymphoreticular tissues of an infected cow find their way into products consumed by humans. Transmissions that might have occurred in the past would be difficult to detect because meat products are generally not distributed in a way that results in detectable geographic clusters.

Barring the discovery of a specific molecular signature (as in variant CJD), the most convincing clue to an association will come from the observation of trends over time of the incidence of typical and atypical BSE and of sporadic and variant CJD. With 4 diseases, each of which could have increasing, unchanging, or decreasing trends, there could be 81 (34) possible different combinations. However, it is highly likely that the trends for typical BSE and variant CJD will both decrease in parallel as feed bans continue to interrupt recycled contamination. The remaining combinations are thus reduced to 9 (32), and some of them could be highly informative.

For example, if the incidence of atypical BSE declines in parallel with that of typical BSE, its candidacy as a sporadic form of disease would be eliminated (because sporadic disease would not be influenced by current measures to prevent oral infection). If, on the other hand, atypical BSE continues to occur as typical BSE disappears, this would be a strong indication that it is indeed sporadic, and if in addition at least 1 form of what is presently considered as sporadic CJD (such as the type 2 M/V subtype shown to have a Western blot signature like BASE) were to increase, this would suggest (although not prove) a causal relationship (Figure 5).

Recognition of the different forms of BSE and CJD depends upon continuing systematic testing for both bovines and humans, but bovine testing will be vulnerable to heavy pressure from industry to dismantle the program as the commercial impact of declining BSE cases ceases to be an issue. Industry should be aware, however, of the implications of sporadic BSE. Its occurrence would necessitate the indefinite retention of all of the public health measures that exclude high-risk bovine tissues from the animal and human food chains, whereas its nonoccurrence would permit tissues that are now destroyed to be used as before, once orally acquired BSE has disappeared.

Bovine Amyloid Spongiform Encephalopathy (BASE) is an atypical BSE straindiscovered recently in Italy, and similar or different atypical BSE caseswere also reported in other countries. The infectivity and phenotypes ofthese atypical BSE strains in humans are unknown. In collaboration withPierluigi Gambetti, as well as Maria Caramelli and her co-workers, we haveinoculated transgenic mice expressing human prion protein with brainhomogenates from BASE or BSE infected cattle. Our data shows that about halfof the BASE-inoculated mice became infected with an average incubation timeof about 19 months; in contrast, none of the BSE-inoculated mice appear tobe infected after more than 2 years. ***These results indicate that BASE istransmissible to humans and suggest that BASE is more virulent thanclassical BSE in humans.

SummaryBackground Concerns have been raised that variant Creutzfeldt-Jakob disease (vCJD) might be transmissible by blood transfusion. Two cases of prion infection in a group of known recipients of transfusion from donors who subsequently developed vCJD were identified post-mortem and reported in 2004. Another patient from this at-risk group developed neurological signs and was referred to the National Prion Clinic.

Methods The patient was admitted for investigation and details of blood transfusion history were obtained from the National Blood Service and Health Protection Agency; after diagnosis of vCJD, the patient was enrolled into the MRC PRION-1 trial. When the patient died, brain and tonsil tissue were obtained at autopsy and assessed for the presence of disease-related PrP by immunoblotting and immunohistochemistry.

Findings A clinical diagnosis of probable vCJD was made; tonsil biopsy was not done. The patient received experimental therapy with quinacrine, but deteriorated and died after a clinical course typical of vCJD. Autopsy confirmed the diagnosis and showed prion infection of the tonsils.

Interpretation This case of transfusion-associated vCJD infection, identified ante-mortem, is the third instance from a group of 23 known recipients who survived at least 5 years after receiving a transfusion from donors who subsequently developed vCJD. The risk to the remaining recipients of such tranfusions is probably high, and these patients should be offered specialist follow-up and investigation. Tonsil biopsy will allow early and pre-symptomatic diagnosis in other iatrogenically exposed individuals at high risk, as in those with primary infection with bovine spongiform encephalopathy prions.

A special "50 STATE CONFERENCE CALL" to discuss BSE (BovineSpongiform Encephalopathy) issues for Food and Drug Administration(FDA) regulated animal feed products in the United States andimported animal feeds. The conference call willdiscuss the FDA proposed response to the current BSE issue and theassistance needed from state feed and agriculture programs. THISISSUE MAY IMPACT ALL STATES AND ALL ANIMAL FEED AND PRODUCTIONINDUSTRIES.

The 50 State call is scheduled for Tuesday, January 9, 2001 from1:00-2:00 pm EST. Any state agency responsible for animal feed issueswishing to participate should call 1-888-273-9887 and ask to beconnected to the "50 State BSE Call". The conference host operatorwill explain how to participate, including asking questions duringthe call. If possible, please coordinate within your state to utilizeonly one phone line per state agency.

We request that you forward this message to your agency managementand feed coordinators or other agencies or departments who may beresponsible for any animal feed issues related to FDA regulatedproducts.

The agenda will be as follows:

1. Center For Veterinary Medicine (FDA) - Discussion of the problemrelated to BSE events in Europe and the impact on US feed ingredientsfor animals and feed operations. Discussion of the proposedactions/inspections/compliance of licensed and unlicensed feed mills,commercial feed manufacturers, animal feed imports, renderer's,protein blenders, on-farm mixers, and ruminant feeders.

2. Office of Regional Operations (FDA) - Discussion ofcontracting/working with states to inspect the universe of feedmills/industry for "Animal Proteins Prohibited from Use in AnimalFeed". Discussion of working with FDA field offices.

3. Questions and answers.

Richard H. Barnes, DirectorDivision of Federal-State Relations (HFC-150)5600 Fishers Lane Room 1207Rockville, Md. 20857ph: (301) 827-6906 FAX: (301) 443-2143Email: [log in to unmask] http://lists.ifas.ufl.edu/cgi-bin/wa.exe?A2=ind0101&L=sanet-mg&P=13410 Subject: BSE--U.S. 50 STATE CONFERENCE CALL Jan. 9, 2001 Date: Tue, 9 Jan 2001 16:49:00 -0800 From: "Terry S. Singeltary Sr." Reply-To: Bovine Spongiform Encephalopathy To: BSE-L@uni-karlsruhe.de ######### Bovine Spongiform Encephalopathy ######### Greetings List Members, I was lucky enough to sit in on this BSE conference call today and even managed to ask a question. that is when the trouble started. I submitted a version of my notes to Sandra Blakeslee of the New York Times, whom seemed very upset, and rightly so. "They tell me it is a closed meeting and they will release whatever information they deem fit. Rather infuriating." and i would have been doing just fine, until i asked my question. i was surprised my time to ask a question so quick. (understand, these are taken from my notes for now. the spelling of names and such could be off.) [host Richard Barns] and now a question from Terry S. Singeltary of CJD Watch. [TSS] yes, thank you, U.S. cattle, what kind of guarantee can you give for serum or tissue donor herds? [no answer, you could hear in the back ground, mumbling and 'we can't. have him ask the question again.] [host Richard] could you repeat the question? [TSS] U.S. cattle, what kind of guarantee can you give for serum or tissue donor herds? [not sure whom ask this] what group are you with? [TSS] CJD Watch, my Mom died from hvCJD and we are tracking CJD world-wide. [not sure who is speaking] could you please disconnect Mr. Singeltary [TSS] you are not going to answer my question? [not sure whom speaking] NO from this point, i was still connected, got to listen and tape the whole conference. at one point someone came on, a woman, and ask again; [unknown woman] what group are you with? [TSS] CJD Watch and my Mom died from hvCJD we are trying to tract down CJD and other human TSE's world wide. i was invited to sit in on this from someone inside the USDA/APHIS and that is why i am here. do you intend on banning me from this conference now? at this point the conference was turned back up, and i got to finish listening. They never answered or even addressed my one question, or even addressed the issue. BUT, i will try and give you a run-down for now, of the conference. IF i were another Country, I would take heed to my notes, BUT PLEASE do not depend on them. ask for transcript from; RBARNS@ORA.FDA.GOV 301-827-6906 he would be glad to give you one ;-) snip...full text ; http://www.fda.gov/OHRMS/DOCKETS/DOCKETS/96n0417/96N-0417-EC-2.htm http://www.fda.gov/OHRMS/DOCKETS/AC/01/slides/3681s2_09.pdf Volume 12, Number 12–December 2006

Sporadic CJDThe possibility that at least some cases of apparently sporadic CJD might be due to infection by sporadic cases of BSE cannot be dismissed outright. Screening programs needed to identify sporadic BSE have yet to be implemented, and we know from already extant testing programs that at least a proportion of infected animals have no symptoms and thus would never be identified in the absence of systematic testing. Thus, sporadic BSE (or for that matter, sporadic disease in any mammalian species) might be occurring on a regular basis at perhaps the same annual frequency as sporadic CJD in humans, that is, in the range of 1 case per million animals.

Whether humans might be more susceptible to atypical forms of BSE cannot be answered at this time. Experimentally transmitted BASE shows shorter incubation periods than BSE in at least 1 breed of cattle, bovinized transgenic mice, and Cynomolgus monkeys (12,13). In humanized transgenic mice, BASE transmitted, whereas typical BSE did not transmit (13). Paradoxically, the other major phenotype (H) showed an unusually long incubation period in bovinized transgenic mice (12).

The limited experimental evidence bearing on a possible relationship between BSE and sporadic CJD is difficult to interpret. The original atypical BASE strain of BSE had a molecular protein signature very similar to that of 1 subtype (type 2 M/V) of sporadic CJD in humans (5). In another study, a strain of typical BSE injected into humanized mice encoding valine at codon 129 showed a glycopattern indistinguishable from the same subtype of sporadic CJD (15). In a third study, the glycopatterns of both the H and L strains of atypical BSE evidently did not resemble any of the known sporadic CJD subtypes (12).

To these molecular biology observations can be added the epidemiologic data accumulated during the past 30 years. The hypothesis that at least some cases of apparently sporadic CJD are due to unrecognized BSE infections cannot be formally refuted, but if correct, we might expect by now to have some epidemiologic evidence linking BSE to at least 1 cluster of apparently sporadic cases of CJD. Although only a few clusters have been found (and still fewer published), every proposed cluster that has been investigated has failed to show any common exposure to bovines. For that matter, no common exposure has been shown to any environmental vehicles of infection, including the consumption of foodstuffs from bovine, ovine, and porcine sources, the 3 livestock species known to be susceptible to transmissible spongiform encephalopathies. Additional negative evidence comes from several large case-control studies in which no statistically significant dietary differences were observed between patients with sporadic CJD and controls (16,17).

On the other hand, the difficulty of establishing a link between BSE and CJD may be compounded by our ignorance of the infectious parameters of a sporadic form of BSE (e.g., host range, tissue distribution of infectivity, route of transmission, minimum infectious dose for humans, whether single or multiple). Presumably, these parameters would resemble those of variant CJD; that is, high infectivity central nervous system and lymphoreticular tissues of an infected cow find their way into products consumed by humans. Transmissions that might have occurred in the past would be difficult to detect because meat products are generally not distributed in a way that results in detectable geographic clusters.

Barring the discovery of a specific molecular signature (as in variant CJD), the most convincing clue to an association will come from the observation of trends over time of the incidence of typical and atypical BSE and of sporadic and variant CJD. With 4 diseases, each of which could have increasing, unchanging, or decreasing trends, there could be 81 (34) possible different combinations. However, it is highly likely that the trends for typical BSE and variant CJD will both decrease in parallel as feed bans continue to interrupt recycled contamination. The remaining combinations are thus reduced to 9 (32), and some of them could be highly informative.

For example, if the incidence of atypical BSE declines in parallel with that of typical BSE, its candidacy as a sporadic form of disease would be eliminated (because sporadic disease would not be influenced by current measures to prevent oral infection). If, on the other hand, atypical BSE continues to occur as typical BSE disappears, this would be a strong indication that it is indeed sporadic, and if in addition at least 1 form of what is presently considered as sporadic CJD (such as the type 2 M/V subtype shown to have a Western blot signature like BASE) were to increase, this would suggest (although not prove) a causal relationship (Figure 5).

Recognition of the different forms of BSE and CJD depends upon continuing systematic testing for both bovines and humans, but bovine testing will be vulnerable to heavy pressure from industry to dismantle the program as the commercial impact of declining BSE cases ceases to be an issue. Industry should be aware, however, of the implications of sporadic BSE. Its occurrence would necessitate the indefinite retention of all of the public health measures that exclude high-risk bovine tissues from the animal and human food chains, whereas its nonoccurrence would permit tissues that are now destroyed to be used as before, once orally acquired BSE has disappeared.

Bovine Amyloid Spongiform Encephalopathy (BASE) is an atypical BSE straindiscovered recently in Italy, and similar or different atypical BSE caseswere also reported in other countries. The infectivity and phenotypes ofthese atypical BSE strains in humans are unknown. In collaboration withPierluigi Gambetti, as well as Maria Caramelli and her co-workers, we haveinoculated transgenic mice expressing human prion protein with brainhomogenates from BASE or BSE infected cattle. Our data shows that about halfof the BASE-inoculated mice became infected with an average incubation timeof about 19 months; in contrast, none of the BSE-inoculated mice appear tobe infected after more than 2 years. ***These results indicate that BASE istransmissible to humans and suggest that BASE is more virulent thanclassical BSE in humans.